二氧化碳还原电催化剂的结构设计及性能研究进展

随着人类社会工业化进程的推进, 化石能源被过度消耗, 人类向大气中排放过量的二氧化碳, 造成能源危机和环境问题. 通过电催化二氧化碳还原反应来制备高附加值精细化学品是积极探索建立人工碳循环的方向之一, 引起了基础研究与工业应用领域研究者的广泛关注. 设计与制备具有高活性、高选择性和高稳定性的电催化剂对于实现二氧化碳高效还原具有重要意义. 近年来, 关于催化剂与电极材料的结构设计和应用案例有许多报道, 取得了显著的进步. 分别从尺寸效应、表面特性、缺陷工程和多级结构四个方面对催化剂结构与电极结构的调控策略进行了综述, 并对电催化二氧化碳还原领域的发展进行了展望.     

基于流动池的电化学二氧化碳还原研究进展

采用电化学方法将二氧化碳（CO₂）还原转化为基础化学品或碳基燃料是目前极具前景的碳资源利用新方式. 考虑到该技术未来的发展方向和大规模应用需求,人们亟需开发具有高转化效率和高稳定性的电解设备. 在本文中,作者详细介绍了现阶段发展的两种流动池的结构特点及性能优势,阐述了每种反应体系的内在局限性, 深入分析了整个反应体系所用组件（电解池、气体扩散电极、离子交换膜）对于性能的影响. 最后,针对目前该领域存在的挑战及未来发展趋势进行了总结与展望.     

酸性条件下二氧化碳高效电还原策略（英文）

二氧化碳电还原技术可以将可再生电能与温室气体二氧化碳转化为高价值燃料和化学品.选择性、能量转化效率、碳利用效率和可持续性是评价二氧化碳电还原技术是否具有工业应用前景的主要指标.在碱性或中性电解液中进行二氧化碳电还原,由于部分二氧化碳在阴极转化为碳酸盐,导致碳利用效率降低.碱性电解液和中性电解液还分别存在电解液再生过程耗能巨大和溶液电阻较高等问题.这些因素导致使用碱性和中性电解液的二氧化碳电还原技术能量转化效率低下.最近,酸性条件下二氧化碳电还原技术有望提高碳利用效率和能量利用效率,成为研究热点.然而,在酸性条件下提升二氧化碳还原选择性具有挑战.前期研究已发展了多种策略以抑制酸性条件下的氢离子还原反应并促进二氧化碳还原反应,但研究者对于酸性条件下的阳离子效应以及局域pH效应等基础科学问题认识尚不一致.此外,气体扩散电极内的碳酸氢盐盐析问题仍限制着酸性条件下二氧化碳还原电解系统的可持续性.因此,亟需对促进酸性条件下二氧化碳电还原的不同策略及可能机制进行总结,并探讨进一步提升电解系统可持续性的潜在路径.本文首先概述了酸性条件下二氧化碳电还原技术的提出及发展历程,对比了碱性、中性和酸性电解液中...     

三相界面电催化二氧化碳还原研究进展

电催化二氧化碳还原是能源化学及催化科学的研究重点与难点.气-固-液三相界面模型作为物理化学中的基本概念,近年来被越来越多地应用于电催化二氧化碳还原反应的研究,其相比于传统固-液两相体系表现出了诸多优点.本综述阐述了三相界面电催化二氧化碳还原研究进展,对三相界面电催化体系进行分类及原理探究.再具体到二氧化碳还原反应,讨论...     

二氧化碳电还原制草酸研究进展

近年来, 二氧化碳过量排放所引发的全球变暖等气候问题引起了全世界的广泛关注, 碳减排已成为人类社会可持续发展面临的共同挑战. 利用电化学方法将二氧化碳转化为高附加值化学品是实现碳减排和二氧化碳高附加值利用的理想途径之一, 但仍面临能耗高、 二氧化碳转化率低、 产物选择性差和难分离等问题. 本文以电还原二氧化碳制草酸为例, 从反应机理、 催化剂、 电解液、 催化电极及反应器等方面介绍该反应的研究进展, 对当前二氧化碳电还原制草酸存在的关键问题进行了分析, 并对其未来研究方向进行了展望.     

氧化还原刻蚀铜表面对二氧化碳电催化还原性能的研究

大规模化石燃料的使用排放了大量的二氧化碳（CO₂）,导致环境中二氧化碳的含量急剧增加. 为了降低大气中二氧化碳的含量,以电催化的方法将二氧化碳转化为有用的化工原料和燃料是解决能源和环境问题的重要途径. 本文主要利用氧化还原刻蚀法,在铜表面形成复合纳米结构,用于二氧化碳的电催化还原反应研究. 首先,作者通过一定浓度的三氯化铁（FeCl₃）溶液与铜片的氧化还原反应,在刻蚀铜表面时形成具有立方体结构的氯化亚铜纳米材料,用于二氧化碳的电催化还原反应. 为了研究反应时间对催化性能的影响,作者通过改变反应时间（1、2、3和4 h）合成了不同结构的铜基催化剂. 研究发现,在反应3 h后,Cu-3h催化剂对二氧化碳的电催化还原具有较小的起始电压（-0.3 V vs. RHE）和较大的电流密度值,表现出了较强的还原能力. 经检测,所得到主要还原产物为一氧化碳（CO）和甲烷（CH₄）. 在-0.6 V时,二氧化碳催化还原的法拉第效率可达到60%,表明以氧化还原法刻蚀铜表面具有较好的改善二氧化碳电催化还原的能力.     

石墨烯基二氧化碳电化学还原催化剂的研究进展

利用电催化技术将CO₂转化为小分子燃料或高值化学品是实现原子经济、构建人工碳循环的绿色能源技术之一。电催化还原CO₂ (ECR)的反应条件温和、产物多样(C₁、C₂和C₂₊),有极大的发展潜力。然而,ECR技术面临一些需要解决的挑战性问题,包括电极过电势高、C₂及C₂₊产物选择性低、伴随析氢反应等。解决这些问题的关键在于创制低成本、高性能电催化剂。近年来,石墨烯基电催化剂的研究成为ECR领域的热点之一,原因包括：1)在电化学环境中稳定性好;2)表面原子、电子结构可调,进而实现材料催化活性的调控;3)维度可调,易暴露较大的比表面积和形成层次孔结构;4)耦合石墨烯的高导电性与特定材料的高活性,可协同提升ECR催化性能。本文评述了石墨烯基材料在ECR中的研究进展,详述了石墨烯基电催化剂的构筑方法,探讨并梳理了石墨烯的点/线缺陷、表面官能团、掺杂原子构型、金属单原子种类、材料表界面性质等与ECR性能之间的本征构效关系。最后展望了石墨烯基催化剂在ECR领域中的挑战和未来发展。     

铋基二氧化碳还原电催化材料研究进展

二氧化碳（CO₂）作为一种经济、安全、可再生的碳资源化合物,其高效回收利用一直是全社会关注的焦点. 利用电化学方法,将CO₂还原转化生成一系列高附加值的化学品或燃料,对于缓解能源与环境双重压力具有重要的现实意义. 本论文介绍了电化学CO₂还原反应的基本原理与过程,综述了近年来铋基催化材料的发展现状,重点对这类催化材料的制备合成、结构调控、催化反应机理研究等方面进行了总结,最后对其未来发展方向进行了探讨与展望.     

用于二氧化碳电化学还原反应的铜基催化剂研究进展

二氧化碳（CO₂）电催化还原对于解决目前日益严重的能源危机和环境污染等问题具有重要的意义,并且能产生一定经济效益. 本文简要概述了水溶液体系中电化学还原CO₂的发展现状,从铜基催化剂的结构/形貌两方面着手,介绍了近年来的最新研究进展. 最后,结合当前发展状况,从能源和经济等角度出发,对未来铜基电极材料研究进行了展望.     

High Selectivity for Ethylene from Carbon Dioxide Reduction over Copper Nanocube Electrocatalysts

Nanostructured surfaces have been shown to greatly enhance the activity and selectivity of many different catalysts. Here we report a nanostructured copper surface that gives high selectivity for ethylene formation from electrocatalytic CO₂ reduction. The nanostructured copper is easily formed in situ during the CO₂ reduction reaction, and scanning electron microscopy (SEM) shows the surface to be dominated by cubic structures. Using online electrochemical mass spectrometry (OLEMS), the onset potentials and relative selectivity toward the volatile products (ethylene and methane) were measured for several different copper surfaces and single crystals, relating the cubic shape of the copper surface to the greatly enhanced ethylene selectivity. The ability of the cubic nanostructure to so strongly favor multicarbon product formation from CO₂ reduction, and in particular ethylene over methane, is unique to this surface and is an important step toward developing a catalyst that has exclusive selectivity for multicarbon products.     

Boosting CO2 Electroreduction on N,P-Co-doped Carbon Aerogels

Electroreduction of CO₂ to CO powered by renewable electricity is a possible alternative to synthesizing CO from fossil fuel. However, it is very hard to achieve high current density at high faradaic efficiency (FE). Here, the first use of N,P-co-doped carbon aerogels (NPCA) to boost CO₂ reduction to CO is presented. The FE of CO could reach 99.1 % with a partial current density of −143.6 mA cm⁻², which is one of the highest current densities to date. NPCA has higher electrochemical active area and overall electronic conductivity than that of N- or P-doped carbon aerogels, which favors electron transfer from CO₂ to its radical anion or other key intermediates. By control experiments and theoretical calculations, it is found that the pyridinic N was very active for CO₂ reduction to CO, and co-doping of P with N hinder the hydrogen evolution reaction (HER) significantly, and thus the both current density and FE are very high.     

Catalysis of Carbon Dioxide Photoreduction on Nanosheets: Fundamentals and Challenges

The transformation of CO₂ into fuels and chemicals by photocatalysis is a promising strategy to provide a long‐term solution to mitigating global warming and energy‐supply problems. Achievements in photocatalysis during the last decade have sparked increased interest in using sunlight to reduce CO₂. Traditional semiconductors used in photocatalysis (e.g. TiO₂) are not suitable for use in natural sunlight and their performance is not sufficient even under UV irradiation. Some two‐dimensional (2D) materials have recently been designed for the catalytic reduction of CO₂. These materials still require significant modification, which is a challenge when designing a photocatalytic process. An overarching aim of this Review is to summarize the literature on the photocatalytic conversion of CO₂ by various 2D materials in the liquid phase, with special attention given to the development of novel 2D photocatalyst materials to provide a basis for improved materials.     

Perfluorinated Covalent Triazine Framework Derived Hybrids for the Highly Selective Electroconversion of Carbon Dioxide into Methane

Developing cost‐effective electrocatalysts for high‐selectivity CO₂ electroreduction remains challenging. We herein report a perfluorinated covalent triazine framework (CTF) electrocatalyst that displays very high selectivity in the electroreduction of CO₂ to CH₄ with a faradaic efficiency of 99.3 % in aqueous electrolyte. Systematic characterization and electrochemical studies, in combination with density functional theory calculations, demonstrate that the presence of both nitrogen and fluorine in the CTF provides a unique pathway that is inaccessible with the individual components for CO₂ electroreduction.     

Boosting CO2 Electroreduction on N,P‐Co‐doped Carbon Aerogels

Electroreduction of CO₂ to CO powered by renewable electricity is a possible alternative to synthesizing CO from fossil fuel. However, it is very hard to achieve high current density at high faradaic efficiency (FE). Here, the first use of N,P‐co‐doped carbon aerogels (NPCA) to boost CO₂ reduction to CO is presented. The FE of CO could reach 99.1 % with a partial current density of ?143.6 mA cm^?2, which is one of the highest current densities to date. NPCA has higher electrochemical active area and overall electronic conductivity than that of N‐ or P‐doped carbon aerogels, which favors electron transfer from CO₂ to its radical anion or other key intermediates. By control experiments and theoretical calculations, it is found that the pyridinic N was very active for CO₂ reduction to CO, and co‐doping of P with N hinder the hydrogen evolution reaction (HER) significantly, and thus the both current density and FE are very high.     

A Water-Soluble Sodium Pectate Complex with Copper as an Electrochemical Catalyst for Carbon Dioxide Reduction

A selective noble-metal-free molecular catalyst has emerged as a fruitful approach in the quest for designing efficient and stable catalytic materials for CO₂ reduction. In this work, we report that a sodium pectate complex of copper (PG-NaCu) proved to be highly active in the electrocatalytic conversion of CO₂ to CH₄ in water. Stability and selectivity of conversion of CO₂ to CH₄ as a product at a glassy carbon electrode were discovered. The copper complex PG-NaCu was synthesized and characterized by physicochemical methods. The electrochemical CO₂ reduction reaction (CO₂RR) proceeds at −1.5 V vs. Ag/AgCl at ~10 mA/cm² current densities in the presence of the catalyst. The current density decreases by less than 20% within 12 h of electrolysis (the main decrease occurs in the first 3 h of electrolysis in the presence of CO₂). This copper pectate complex (PG-NaCu) combines the advantages of heterogeneous and homogeneous catalysts, the stability of heterogeneous solid materials and the performance (high activity and selectivity) of molecular catalysts.     

Selective and Efficient Reduction of Carbon Dioxide to Carbon Monoxide on Oxide‐Derived Nanostructured Silver Electrocatalysts

In this work, the selective electrocatalytic reduction of carbon dioxide to carbon monoxide on oxide‐derived silver electrocatalysts is presented. By a simple synthesis technique, the overall high faradaic efficiency for CO production on the oxide‐derived Ag was shifted by more than 400 mV towards a lower overpotential compared to that of untreated Ag. Notably, the Ag resulting from Ag oxide is capable of electrochemically reducing CO₂ to CO with approximately 80 % catalytic selectivity at a moderate overpotential of 0.49 V, which is much higher than that (ca. 4 %) of untreated Ag under identical conditions. Electrokinetic studies show that the improved catalytic activity is ascribed to the enhanced stabilization of COOH^. intermediate. Furthermore, highly nanostructured Ag is likely able to create a high local pH near the catalyst surface, which may also facilitate the catalytic activity for the reduction of CO₂ with suppressed H₂ evolution.